Lecture 10

Question 1

What are population genetics

Answer 1

The study of how genetic variation is distributed in a population and how it changes over time, to an extend its like evolution
It’s studying the changes in genotype and allele frequencies
Can even be used to compare populations

Question 2

What can cause changes in population levels (like of a certain gene or allele)

Answer 2

Mutation
Migration
Natural Selection
Genetic Drift
These all interact (happen at the same time not separately) so they all contribute to evolution in a big picture way

Question 3

What’s a haplotype

Answer 3

The genetic info/pattern on one of a pair of chromosomes

Question 4

What’s a gene pool model

Answer 4

Basically just when you have a representation of the individuals in a population and what their different genotypes are for a given gene

Question 5

How do we calculate genotype frequencies

Answer 5

Get the total and they genotypes, count those too
Divide the number of homozygous dom by the total, gives you a decimal, repeat for other genotypes and note that the total of these decimals should add to one, thats just the notation

Question 6

How can we calculate allelic frequency

Answer 6

Same way as genotype frequency except each individual has 2 alleles, so the denominator is double the individuals

Question 7

What notation is used in allele frequencies

Answer 7

P denotes allele frequency of the dominant allele and q denotes the allele frequency of the recessive allele

Question 8

How can you convert genotype frequency to allele frequency (like if those values are all thats given)

Answer 8

P (allelic frequency of dom)= f AA + (1/2) f Aa
Q (allelic frequency of rec)= f aa + (1/2) f Aa
Idea is that you’re using the genetic frequency of the homozygote which still applies and then only half of the heterozygous because it only contains one allele like the one you want
Note: these have to add up to 1 too so you really only need one

Question 9

Under what conditions can you predict/calculate the genotype frequency of the next generation

Answer 9

There must be random mating, no mutating, no selection, no migration and no drift, so basically eliminating all factors that push evolution
And you obviously need to have the info of the current generation

Question 10

What are the hardy-Weinberg proportions

Answer 10

Proportions used to estimate the genotype frequency of the next generation, he has 2 equations that “work” assuming all his conditions are met
Freq (AA) is p^2, Freq (Aa) is 2pq and the Freq (aa) is q^2
This is basically p and q representation of what you get by crossing two hétérozygotes
Note this only applies to 2 alleles

Question 11

What happens when a population reaches Hardy Weinberg proportions

Answer 11

It reaches a sort of equilibrium where the frequencies will remain unchanged because (in his bubble) theres still random mating, no evolutionary forces
This equilibrium is good as long as conditions are respected

Question 12

What does hardy Weinberg look like for 3 alleles

Answer 12

As before the homozygous, for whichever, is p^2, where P is the allelic freq
As for the heterozygous is the product of the allelic frequencies of the alleles times 2, so 2 x p1 x p2
The sum is always 1